FIG. 1 depicts a conventional method 10 for fabricating a magnetoresistive sensor in magnetic recording technology applications. The method 10 typically commences after a conventional magnetoresistive or tunneling magnetoresistive (TMR) stack has been deposited. The conventional read sensor stack typically includes an antiferromagnetic (AFM) layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. In addition, seed and/or capping layers may be used. The conventional magnetoresistive stack resides on an underlayer, which may be a substrate.
The conventional method 10 commences by providing a conventional mask for the read sensor, via step 12. The mask provided is either a conventional hard mask or a conventional photoresist mask. The conventional photoresist mask covers the region from which the conventional magnetoresistive sensor is to be formed, as well as a portion of the transducer distal from the sensor termed the field region
The magnetoresistive structure is defined using the conventional mask, via step 14. Step 14 typically includes ion milling the transducer. Thus, the portion of the magnetoresistive stack exposed by the conventional mask is removed. The magnetoresistive structure being defined may be a magnetoresistive sensor for a read transducer.
The hard bias material(s), such as CoPt, are deposited, via step 16. In addition, seed and/or capping layers may be provided in step 16. The hard bias material(s) and other layers are deposited while the conventional hard mask is in place. In addition, a shallow mill may be performed as part of providing the hard bias structure. A capping layer may be deposited after the shallow ion mill is completed. The capping layer typically includes a noble metal such as Ru and/or Ta.
The conventional mask may then be removed, via step 18. For a conventional photoresist mask, step 18 may include performing a lift-off. For a hard mask, another process, such as ion milling may be used. A planarization such as a chemical mechanical planarization (CMP) is performed, via step 20. The stripe height of the sensor is then defined, via step 22. Note that in some instances, the stripe height may be defined in step 22 prior to the steps 12-20. An insulator such as aluminum oxide is deposited on the transducer, via step 24.
Although the conventional method 10 allows the conventional transducer to be fabricated, there are several drawbacks. The current trend in magnetic recording is to decreased track widths. The track width is approaching the sub-thirty micron range. At such low thicknesses, a conventional photoresist mask is consumed quickly in part because faceting of the photoresist mask may be significant at lower track widths. Thus, the desired track width may not be able to be achieved is a conventional photoresist mask is provided in step 12. If a conventional hard mask is used instead, the hard mask may only be removed by a CMP and/or ion milling. This process may be difficult particularly for large areas for which the CMP capability may be limited and ion milling may be less effective. Further, the hard mask material may be stressful. A hard mask under stress may cause delamination of the magnetoresistive sensor film, particularly during the planarization in step 20. Thus, the conventional method may not be capable of producing a read sensor at higher magnetic recording densities and the attendant lower track widths.
Accordingly, what is needed is a system and method for improving the fabrication of a magnetic recording read transducer.